Furniture leg floor protectors have been in use for many years to avoid damage to the floor when a piece of furniture is moved. They also reduce noise in the classroom where children move their desks and chairs around often making an irritating noise.
Some known floor protectors for furniture legs comprise a disk of synthetic plastics material, or metal, which can be fixed to the end of the leg by adhesive or a screw. Attached to the underside of the disk is a pad of felt or other suitable protective material which contacts the floor. For example, US 2005/0003723 (Brouard et al.) discloses floor protectors for fastening to the underside of the foot of the leg by adhesive or by a hook-and-loop fastener (e.g., Velcro™), so that it can be replaced more easily. US 2008/0148522 (Beshore), as another example, discloses a three-part floor protector which comprises an inverted cup for securing by its base to the furniture leg by means of a screw. Engaged in the inverted cup are a glide of non-abrasive synthetic plastics material and an interposed resilient washer. US 2007/0234507 (Vorpahl) discloses yet another example in the form of a glide assembly which has interchangeable hard and soft bases and several attachment devices which can be adapted to the foot of the furniture leg and the type of floor.
Sometimes, it is not practical or desirable to fasten the floor protector using a screw fastener or adhesive. For metal or plastics furniture legs having an enlarged foot portion, perhaps in the form of a disk or toroid, or even an adjustable foot or glide fastened by a screw, it is known to use a slip-on floor protector in the form of a unitary boot of rubber or synthetic plastics material which fits over the foot/glide and grips its upper surface. The boot may itself contact the floor or may carry a pad of felt or other protection material. Examples of slip-on floor protectors are disclosed in U.S. Pat. No. 2,865,133 (Hoven et al.), U.S. Pat. No. 6,405,982 (Ferencz), and U.S. Pat. No. 6,754,934 (Shiffler).
It is also known to use a slip-on floor protector which is generally in the form of a ball with a slit in the top, as disclosed, for example, in US 2007/0220703 (LaPointe et al.). The end of the furniture leg is inserted into the ball so that its foot rests on the interior of the bottom of the ball and the sides of the slit grip the furniture leg.
Because these slip-on floor protectors are relatively short, they may become dislodged relatively easily, especially when used in schools where chairs may be rocked as well as dragged. Also, the boot or ball may be considered to be unsightly.
It is known to use a floor protector having not only a boot portion to fit around the foot of the leg but also an integral tube which will extend upwards along the leg and grip the surface of the leg above the foot. US 2008/0179471 (Verdelli), for example, discloses a tube which is secured to the furniture leg by means of elastic bands or by ribbon or string tied around it. US 2008/0209686 (Lang) also discloses a floor protector secured to the foot or leg by a tie. In one embodiment, the protector has a tube closed at one end (which contacts the floor) and a tie wrapped around portions the tube near its other end to fasten it tightly to the leg. In an alternative embodiment, the tie passes through upstanding flanges of a boot to draw them closed over the upper surface of the foot. The use of ties may not be acceptable because they may come undone and may be unsightly.
Some floor protectors rely, at least primarily, upon elasticity of the sleeve to grip the leg of the furniture. For example, U.S. Pat. No. 7,124,986 (Bailey) discloses a floor protector comprising an elastomeric sleeve with one end closed, at least partially, to form a bottom to which is glued or stitched a pad of felt or other protective material. The sleeve can be stretched to fit onto the furniture leg. US 2004/0123421 (Bushey) discloses a floor protector comprising a hemispherical base and a sleeve for fitting around the furniture leg. The sleeve has resilient projections in the form of splines, flutes or leaves, which extend radially inwardly to grip the leg. These projections may complicate manufacture yet not provide adequate grip, especially when the protector has been in use a long time and repeated flexing and aging have reduced the elasticity of the sleeve. Similarly, US 2004/0123421 discloses a floor protector with a corrugated sleeve having folds therein to increase friction. It would appear, however, that the complexity of the molding process could make this option uneconomical.
US 2005/0115022 (Desmarais—present inventor) discloses a floor protector having a sleeve with internal splines to grip the leg. The problem of stretching and enlargement of the sleeve, causing it to loosen was addressed by means of a flexible coupling between upper and lower portions of the sleeve, allowing the leg to tilt while the pad beneath the foot of the leg remained flat upon the floor. Nevertheless, this approach too is not entirely satisfactory because it entails a rather complicated, hence costly, molding configuration.
The trade-off between ease of installation of a floor protector having an elastomeric sleeve and the security of the grip between the sleeve and the furniture leg, especially after the furniture has been dragged or tilted repeatedly during normal usage, was addressed in the present inventor's United States published patent application No. 2008/0258023, which discloses a floor protector having a sleeve which is more elastic at the top than at the bottom. This upper portion can be stretched enough to allow it to be rolled outwards, the leg/foot inserted into the less-elastic lower portion, and the upper portion unrolled onto the leg. Rolling up the stretchable upper sleeve portion facilitates installation, while the stiffer lower sleeve portion firmly grips the lower portion of the leg and provides good stability of the floor-engaging pad. Nevertheless, this arrangement may not be entirely satisfactory if fitted to heavy furniture or, in the case of an occupied chair, tilted and/or dragged, subjecting the sleeve to excessive stress.
The need to protect floors may also arise where the furniture or other movable object is equipped with caster units for ease of movement. In the home or a hospital setting, for example, such caster units may be fitted to beds. In the office setting, many office chairs are mounted upon a pedestal having, typically, five legs each with a caster unit. Some caster wheels are made of hard black synthetic plastics material, for example polyurethane, which may leave marks upon, or physically damage, certain types of flooring. It is known to provide plastic mats beneath such office chairs both to protect the floor and, in some cases, guard against the build-up of static electricity. Disadvantages of such mats, however, is that they are relatively expensive, unsightly and may impair movement of the chairs.
It is known to equip the caster with a cover of relatively soft material which is less likely to cause damage to, or mark, the floor. For example, Products of Maximus LLC markets a caster tire cover under the trademark CasterBooties which involves a leader strap to pull the cover onto a caster in the form of a wheel, an elastic band each side to hold the cover onto the caster, an over flap, an under flap, and Velcro™ fasteners. According to their web site at http://www.tirebooties.com/CasterBooties_Caster_Tire_Covers.html, in addition to being complicated, the cover is not recommended for steel caster wheels or dual wheels and will not fit on casters with wheel brakes. (cf. web page appended to this description.)
United States patent publication No. 2007/0062001 (Bushey et al.) discloses a caster wheel cover comprising a generally cylindrical floor-engaging member having sidewalls projecting from opposite edges to define a channel which receives the outer surface portion of the caster wheel. The cover is installed by wrapping it around the circumference of the caster wheel. In one embodiment, the cover can be opened and closed, like a bracelet, to enable it to be fitted onto the caster wheel. In another embodiment, the cover is a complete circle and one sidewall has notches to allow it to flex and facilitate installation of the cover. Yet another embodiment is a complete circle but with no notches; instead the inner surfaces of the sidewall are laterally spaced from respective sides of the wheel. Such a caster wheel cover in the form of a complete circle, without notches, is marketed by Expanded Technologies LLC under the trademark CasterTire™. According to installation instructions on their web site at http://www.expandedtechnologies.com/caster_tire_inst.html, (cf. web page appended to this description) their caster tire is installed in much the same way that a car tire is installed, using a tire lever to pry the tire over the wheel. The installation instructions include a tip, namely “If having trouble with installation, try placing tires in a bucket of hot tap water. The hot water will make the tires more pliable and easier to install.”
There remains a need, therefore, for a floor protector for a caster that not only is durable and secure once installed, but also can be installed easily and, once worn, replaced easily.
An object of the present invention as applicable to furniture leg floor protectors is to overcome or at least mitigate the above-described deficiencies of such known floor protectors, or at least provide an alternative furniture leg floor protector which combines ease of installation with security once it has been installed.
An object of the present invention as applicable to casters of caster units is to overcome or at least mitigate problems associated with caster covers or tires and to provide a floor protector for casters which combines ease of installation with a secure grip once it has been installed.
To this end, embodiments of the present invention employ shrinkable tubing, for example, heat-shrink tubing, to secure the floor protector directly or indirectly to the leg or caster.
According to the present invention, therefore, there is provided a floor protector having a tube of shrinkable material sized to fit onto a leg portion of a furniture leg or a circumferential surface of a caster attached or attachable to a movable item, the shrinkable material having a shrinkage ratio such that, when shrunken by the application of heat or ultraviolet radiation or by other means, the tubing grips the leg or caster to secure the floor protector thereto.
In this specification, the term “unshrunk” tube/tubing will be used to describe the condition of the tube/tubing before it has been shrunk during installation, and the word “shrunken” will be used to describe the tube/tubing after it has been shrunk. This does not preclude, however, the tube/tubing having been shrunk partially down to the “unshrunk” size before installation commences.
According to a further aspect of the present invention, there is provided a floor protector adapted for use with furniture having at least one leg with a foot portion, the floor protector comprising a tube of shrinkable material that can be shrunk by application of heat, or by other suitable or appropriate means, the tube having at normal room temperatures a predetermined unshrunk cross-sectional size large enough to permit the tube to receive said foot portion and a shrinkage rate sufficient for the tube to be shrunken to a cross-sectional size that is smaller than the foot portion so that, when the tube is placed over the foot portion and shrunken by application of heat or by other means as aforesaid, the tube will conform to and grip the underlying foot portion and secure the floor protector to the foot portion.
According to another aspect of the present invention, there is provided a method of installing a floor protector onto a foot portion of a furniture leg, comprising the steps of fitting over the foot portion a tube of shrinkable material that can be shrunk by application of heat or by other suitable or appropriate means, the tube having a predetermined unshrunk cross-sectional size large enough to receive the foot portion, the shrinkable material having a shrinkage ratio sufficient for the tube to be shrunk to a size smaller than a cross-sectional size of the foot portion, and the step of shrinking the tube by application of heat or by other suitable or appropriate means to cause the tube to shrink at least until the tube has conformed to the underlying surface of the foot portion to such an extent as to grip the foot portion and secure the floor protector to said foot portion.
Preferably, the shrinkable tube is made of heat-shrink material, i.e. a thermoplastic material which shrinks when heated. It is known to use heat-shrink tubing in the electrical industry around connections between electrical conductors and between electrical conductors and terminals, to provide insulation, abrasion resistance and environmental protection. Suitable heat-shrink materials may shrink to as little as one third or one quarter of their original size and may shrink at temperatures which can be obtained using a heat source that is relatively readily available, such as a small butane torch, an electrical hot air heat gun, a paint-stripper or a hair dryer. Generally, commercial hand-held hair driers would be preferred because domestic hair dryers operate at lower air temperatures than commercial hair driers, which limits their use with heat-shrink materials that are commercially available at this time. Nevertheless, use of a domestic hair dryer or other heat source is not precluded if it can provide the required flow of air at a sufficiently high temperature.
According to yet another aspect of the invention, there is provided a method of making a floor protector adapted for use with furniture having at least one leg with an end having a width smaller than a girth adjacent the end, the floor protector comprising a tube of shrinkable material that can be shrunk by application of heat, or by other suitable or appropriate means, the method comprising providing a preform comprising a base portion and an integral tube portion, the cross-sectional size of the tube portion being significantly less than the cross-sectional size of the base portion, and stretching the tube portion to a size sufficient to accommodate said girth.
In embodiments of the foregoing aspects of the invention, at least part of the interior of the tube may be provided with an adhesive so that, once the tube has been fully shrunk, the adhesive bonds the tube to the foot portion and provides additional security against the floor protector being dislodged. Where the tube comprises heat-shrink material, the adhesive may be heat-sensitive (hot-melt) adhesive arranged to melt at a temperature similar to that required to shrink the tube; the hot-melt adhesive being melted (activated) contemporaneously with the shrinking of the tube, i.e., using the same heat source. Once cooled, the adhesive assists in securing the floor protector to the foot portion.
Preferably, the shrinkable tube is installed onto a foot portion having a non-uniform profile, i.e., having lateral protrusions, so that, once the tube has been shrunk, the tube conforms at least partially to the protrusions and provides mechanical resistance to forces acting in the direction of the tubular axis to that would tend to dislodge or remove the floor protector, at least partially.
In preferred embodiments of either aspect of the invention the unshrunken tube is partially or completely closed at one end which carries a pad of protective material, the unshrunken tube being greater in cross-sectional size than the foot portion of the furniture leg and having a length predetermined such that when the tube has been shrunken onto the furniture leg foot portion, a desired grip or frictional force between the tube and the leg or foot portion is sufficient to hold the tube and pad onto the foot portion.
Preferably, the pad is embedded partially into the material of the closed end of the tube, the material of the tube bottom infusing interstices at a surface of the pad juxtaposed to the bottom of the tube. Such embedding of the pad may be attained by molding the tube onto the pad during molding of the floor protector. In preferred embodiments, at least the juxtaposed portion of the pad comprises fibrous material, e.g. felt, preferably wool felt.
Preferably the shrinkable tube material is selected, both in terms of its shrinkage characteristics and dimensions, so that the shrunken tube may conform closely to the exterior of the leg and/or foot portion both to provide a desired gripping force and to avoid, at least to some extent, an unsightly result. The floor protector may be transparent so as to be less noticeable. Suitable shrinkable materials include polyurethane, polyolefin, fluoropolymer (such as fluorinated ethylene propylene (FEP), polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (e.g., Kynar™), polyvinylchloride (PVC), neoprene, silicone elastomer and fluoroelastomer (e.g., Viton™).
According to yet another aspect of the present invention, there is provided a floor protector adapted for use on a caster of a caster unit attachable or attached to an item of furniture or other movable objects, the floor protector comprising a tire of shrinkable material that can be shrunk by a predetermined shrinkage ratio by application of heat or by other suitable means, the tire having, at normal room temperatures, a predetermined unshrunk cross-sectional size that allows the tire to be fitted around the circumference of the caster said cross-sectional size and, the shrinkage ratio being such that, when shrunk, the tire will conform to the circumference of the caster and adhere thereto.
According to a still further aspect of the present invention, there is provided a method of installing a floor protector onto a caster of a caster unit attachable or attached to an item of furniture or other movable equipment, comprising the step of fitting over the circumference of the caster an unshrunk tube of shrinkable material, the shrinkable material having a shrinkage ratio such that, when shrunk, the tire will conform to the caster and adhere thereto, the method further comprising shrinking the tire by application of heat or by other suitable means at least until the tire has conformed to the underlying surface of the caster to such an extent as to secure the floor protector to said underlying surface.
Preferably, the shrinkable tire is made of so-called heat-shrink tubing material which shrinks when heated, for example polyurethane, polyolefin, fluoropolymer (such as fluorinated ethylene propylene (FEP), polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (e.g., Kynar™), polyvinylchloride (PVC), neoprene, silicone elastomer and fluoroelastomer (e.g., Viton™).
The unshrunken tire may have a width that is greater than the axial width of a rim portion of the caster to such an extent that, when the tire has been shrunken, opposite margin portions of the shrunken tire form flanges that extend radially inwards to engage respective opposite sides of the rim portion of the caster to resist axial movement of the tire relative to the caster.
Some casters have an edge profile that is larger in diameter at the middle than the sides. For example, some casters are generally ball-shaped, or generally barrel-shaped, while others have a circumferential ridge around the middle of the circumferential surface of the caster. The width of the tire may be selected so that, once the tire has been shrunken onto the caster, opposite edge portions of the tire will extend radially-inwardly and resist axial movement of the tire relative to the caster wheel. The heat-shrink material will become denser and stiffer as it is shrunk, so the radially inwardly extending portions will provide a mechanical locking effect to resist removal of the floor protector. Where the caster wheel has such an edge profile, the width of the tire may be great enough for opposite edge portions to extend not only radially inwardly to engage opposite sides of the larger-diameter middle of the caster wheel but less than the width of the caster wheel; i.e., there will be no flanges extending inwards on opposite sides of the rim portion of the caster. Conversely, the tire may be wide enough to conform not only with the sides of the larger-diameter middle of the caster wheel (e.g., ridge, rib or lesser-diameter parts of the barrel-shaped surface) but also extend radially inwards on each of the opposite sides of at least a rim portion of the caster.
At least part of the interior surface of the tire may be provided with an adhesive so that, once the tire has been shrunk onto the caster wheel, the adhesive bonds the tire to the caster wheel and provides additional security against the tire being accidentally dislodged, at least partially. Where the tire comprises heat-shrink material, the adhesive may be a heat-sensitive (hot-melt) adhesive that melts at temperatures similar to those required to shrink the tire; the hot-melt adhesive then being melted (activated) contemporaneously with the shrinking of the tire, conveniently using the same heat source.
Preferably the shrinkable tire material is selected, both in terms of its shrinkage characteristics and dimensions, including thickness, so that the shrunken tire may conform closely to the exterior of the caster wheel, both to provide a desired gripping (e.g. frictional) force and avoid, at least to some extent, an unsightly result. The tire material may be transparent, also for aesthetic reasons.
Further features and advantages of floor protectors embodying the present invention will be set out in the following description of preferred embodiments of the invention, taken in conjunction with the accompanying drawings, which descriptions provided by way of example only.